1. Field of the Invention
The present invention relates to the field of microstructure manufacturing as well as treating substrates in semiconductor materials.
2. Description of Related Art
In microelectronics, certain operations, such as bonding operations, require surfaces to be bonded to be as smooth as possible. But the manufacturing of certain devices, particularly the type implementing a membrane or mobile part, may necessitate having surfaces that face each other without adhering to each other because of the need to prevent untimely bonding of the membrane on the facing surface, or because the membrane on the facing surface needs to be able to maintain mobility.
French Patent No. 2 857 953 discloses a process of manufacturing bonded silicon on insulator (“BSOI”) type structures in which a so-called structured zone is made, preventing bonding between surfaces. This type of structure is applicable to MEMS fabrication, and more particularly to situations where a superficial silicon membrane must be released to manufacture sensors. During the release step, which includes an underlying oxide attack, for example, or during operation of the sensor, if the membrane bonds to the substrate, the bonding induces dysfunction of the component. As explained in the document above, a BSOI substrate that includes a rough buried interface avoids this problem, as the roughness of the buried interface prevents any bonding between the membrane and the support.
In French Patent No. 2 857 953, roughening of the surface is accomplished by various techniques, for example by the use of “Unibond® negatives”, produced by the “Smart Cut™” process. Such a process is described in French Patent No. 2 681 472, as well as in B. Aspar et al., “The generic nature of the smart cut process for thin film transfer,” J. of Elec. Material, vol. 30, No. 7, 2001. To obtain the buried roughness adapted to different anti-sticking BSOI substrates, it is necessary to provide negatives having the desired roughness.
Such conventional methods and systems generally have been considered satisfactory for their intended purpose. However, providing a substrate or negative with a particular roughness, or in other words, controlling the amount of roughness provided on a negative or substrate is difficult if not impossible. There still remains a continued need in the art for a method of manufacturing membranes or mobile parts in integrated components wherein the bonding effects above are avoided by providing a specific surface roughness on the components in question. The present invention provides a solution for these problems.